The present invention refers to an adapter apparatus for receiving memory modules.
Personal computers, workstations and servers usually have one or several sockets for receiving memory modules. A memory module is a small board with a plurality of data terminals and a plurality of control terminals and carries one or several RAM devices. The RAM devices of memory modules, which are inserted into sockets of a computer, form together the working memory of the computer. To extend the working memory or to increase its capacity, respectively, additional memory modules can be inserted into free sockets or already existing memory modules can be replaced by memory modules with higher capacity.
In recent years, a standard for memory modules has gained acceptance and found wide distribution, which is generally known by the abbreviation DIMM (DIMM=dual inline memory module). DIMM memory modules from different manufacturers can be used almost arbitrarily in DIMM sockets of computers from different manufacturers, since number, shape and arrangement of data terminals and control terminals, time profiles and levels of data and control signals to be exchanged, a protocol for the transmission of important parameters of a memory module to the computer, etc. are specified.
A user of a computer has advantage that he can change the size of the working memory of the computer and can choose between the products of different manufacturers when buying memory modules.
Different manufacturers offer workstations and servers, which do not use the DIMM standard, but instead customized memory modules, so-called server DIMM memory modules or briefly, xe2x80x9cserver DIMMsxe2x80x9d. For example, a customized server DIMM memory module differs significantly from a standard DIMM memory module in the architecture, in the applied signals and their timing. The most important differences are listed below:
Standard and commodity DIMM memory modules, respectively, have 72 IO channels and input/output terminals, respectively, and data terminals, respectively, as well as various control terminals, terminals for supplying a supply voltage and ground terminals (GND=ground), for example a total of 168 pins and terminals, respectively, for a single data rate (SDR) or 184 pins for a double data rate (DDR). Customized server DIMM memory modules have, for example, the double IO width, i.e. 144 data terminals, various control terminals, terminals for one or several supply voltages, a ground terminal and, for example, a total of 232 terminals.
The DIMM standard provides a LVCMOS clock for SDR, which is transmitted from the computer to the memory module to clock the exchange of data and control signals. In a server DIMM memory module, however, a differential LVPECL clock is provided.
Contrary to standard DIMM memory modules, on server DIMM memory modules, a buffer and a latch, respectively, is provided for addresses, instructions and other control signals to minimize the input capacities for the respective signals. Due to the delayed effect of the latch on the signals, the memory controller provides a timing shifted towards the setup side.
Due to the described differences, it has so far not been possible to use standard DIMM memory modules in computers with server DIMM sockets. This results leads to several disadvantages for the user of such a device. Particularly, the user cannot fall back on the cost effective and easily available standard DIMM memory modules, but is dependent on buying server DIMM memory modules, which are produced in much smaller numbers and are distributed by a much smaller number of computer accessory dealers. Accordingly, the prices of server DIMM memory modules are significantly higher than the prices of standard DIMM memory modules. Additionally, standard DIMM memory modules are usually available much earlier than customized modules, such as the server DIMM memory module. Thus, a user of a computer with server DIMM sockets can use memory modules or memory devices of a new shrink generation only later than a user of a computer with standard DIMM sockets.
Although the described problems have a significant practical relevance for users of computers with server DIMM sockets, so far no solution is known.
It is the object of the present invention to provide an apparatus, which enables the use of memory modules according to a first standard in sockets according to a second standard.
In accordance with a first aspect of the invention, this object is achieved by an adapter apparatus for receiving memory modules, wherein each of the memory modules comprises a plurality of data terminals and a plurality of control terminals, comprising: first data terminals and first control terminals; a first socket for receiving a first memory module with second data terminals and second control terminals, wherein the second data terminals are associated to the data terminals of the first memory module, wherein the second control terminals are associated to the control terminals of the first memory module; a second socket for receiving a second memory module with third data terminals and third control terminals, wherein the third data terminals are associated to the data terminals of the second memory module, wherein the third control terminals are associated to the control terminals of the second memory module; a signal transformation circuit with an input and an output, wherein the input is connected to the first control terminals, and wherein the output is connected to the second control terminals and to the third control terminals, wherein a first group of first data terminals is connected to the second data terminals, and wherein a second group of first data terminals is connected to the third data terminals.
The present invention provides an adapter apparatus for receiving memory modules, wherein each of the memory modules comprises a plurality of data terminals and a plurality of control terminals. The adapter apparatus comprises first data terminals, first control terminals and a first socket for receiving first memory modules with second data terminals and second control terminals, wherein the second data terminals are associated to the data terminals of the first memory modules, and wherein the second control terminals are associated to the control terminals of the first memory modules. Further, the adapter apparatus comprises a second socket for receiving a second memory module with third data terminals and third control terminals, wherein the third data terminals are associated to the data terminals of the second memory module, and wherein the third control terminals are associated to the control terminals of the second memory modules. Further, the adapter apparatus comprises a signal transformation circuit with an input and an output, wherein the input is connected to the first control terminals, and wherein the output is connected to the second control terminals and to the third control terminals. In the adapter apparatus, a first group of first data terminals is connected to the second data terminals, and a second group of first data terminals is connected to the third data terminals.
According to the present invention, memory modules corresponding to a first specification and a first standard, respectively, can be used in a socket corresponding to a second specification and a second standard, respectively. Further, by the present invention, an adaption of the control signals according to the server DIMM specification to the DIMM standard and vice versa is performed in a simple way via a phase locked loop, a latch and an EEPROM. These necessary devices are easily available and enable cost effective production of the adapter apparatus.
It is an advantage of the present invention that it enables a user of an apparatus, such as a computer, with a socket for a memory module with first data terminals and first control terminals, to use memory modules with second data terminals and second control terminals, although the number of first data terminals and the number of second data terminals differ, and although the first control terminals and the second control terminals differ with regard to number, arrangement and the control signals transmitted via them. Thus, the user can fall back on a bigger choice of memory modules and has, if necessary, the possibility to use more powerful and/or less expensive memory modules.
Particularly in the already above-described specific case of the server DIMM sockets of a workstation or a server, the inventive adapter apparatus produces compatibility between standard SDRAM DIMM memory modules on the one hand and the server memory control and the server DIMM socket on the other hand. Additionally, the adapter apparatus has exactly two sockets for the reception of standard DIMM memory modules, whose respective 72 data terminals are combined to 144 data terminals. Thus, standard DIMM memory modules can be used in workstations and servers of the high-end segment. This leads to a cost advantage, since standard DIMM memory modules are available much cheaper than the customized server DIMM memory modules. Further, for analysis purposes, standard DIMM memory modules (such as first modules of a new shrink or a new design level) can be tested in an application of a manufacturer by means of the adapter apparatus, whereby the full functionality in the target system is ensured. Here, the use of the adapter apparatus offers a time advantage, since standard modules are mostly available earlier than customized modules. Further, in reverse engineering and foreign design comparison, standard DIMM memory modules of the competitors can be used. Here, also a time and cost advantage occurs, whereby the adapter apparatus does not cause a performance loss. Respective advantages occur also in the case of different standards and specifications, respectively.
Preferred developments of the present invention are defined in the sub claims.